Expression of Ki67 and CD68+ cells of red bone marrow monocyte sprout under triptorelin administration in the hypothalamic-pituitary-testis regulatory system: the experimental study

Abstract

Background. Red bone marrow (RBM) is the main organ of human haemopoiesis. Monocytopoiesis plays an important role in the formation of transitional states: from normal to pathology and in the transformation of pathological processes from one stage to another. In modern urological practice, the substance triptorelin is widely used for androgen deprivation therapy, according to the recommendations of the European Association of Urology. Ki67, a commercially available monoclonal antibody that reacts with a nuclear antigen detected only in proliferating cells, is used to assess immunohistochemical changes. CD68 is a valuable cytochemical marker for immunostaining of monocytes/macrophages during histochemical analysis of tissues in inflammation, cancer and other immunohistopathological purposes. The purpose of the study is to evaluate the proliferative activity and differentiation of progenitor cells through the expression of Ki67 and CD68+ monocyte sprouting of RBM under chemical castration of central origin in male rats caused by the administration of triptorelin solution with quercetin addition to the diet for one year. Materials and methods. The study was conducted on 60 adult male white rats. They were divided into 3 groups: group I — control (n = 10), group II (n = 25) — subcutaneous injection of triptorelin, group III (n = 25) — subcutaneous injection of triptorelin acetate and quercetin. Immunohistochemical analysis of biopsy specimens was conducted following a standard protocol at the Department of Pathological Anatomy in Sumy State University, under the supervision of the Head of the Department, Prof. Romaniuk A.M. Results. The study evaluated Ki67 expression on microsections of rat red bone marrow through immunohistochemistry, which exclusively reacted with nuclear antigen in the monocyte sprout’s proliferating cells. Irregular changes were revealed depending on the experimental groups and time periods. Immunohistochemical analysis of RBM tissue using anti-CD68 antibodies in the experimental groups revealed a strong positive cytoplasmic response in monocytes and resident macrophages located in the monocyte sprout and surrounding environment. The data of the two experimental groups of RBM had a noticeable proliferating compartment, as evidenced by the high content of mitotically active DNA in them. These data correspond to the results obtained in the experiment with triptorelin, where we found a marked positivity of Ki67, depending on the timing of the experiment and the addition of the flavonoid quercetin. This discrepancy suggests that bone marrow cells that grow and proliferate under normal conditions are guided by natural control mechanisms and may lose their Ki67 expression after leaving the progenitor compartment and entering the differentiation compartment. Conclusions. Triptorelin administration induces hormonal imbalance in the hypothalamus-pituitary-testis-RBM system, resulting in quantitative and qualitative alterations in the cells of the RBM monocytic lineage. The level of cell proliferation, as measured by Ki67, is highest during the third month of observation. Cytoplasmic expression of CD68 is evident in two experimental groups from the third to the sixth month, suggesting activation of immunoreactive cells as they migrate from the progenitor compartment to the differentiation compartment.